Radioactive gold seeds, which are metallic gold formulations without surface coating or modification, have been used for treating cancer since the 1950s. They were used as permanent surgical implants for brachytherapy. To improve the performance and extend the applications of gold seeds, strategies have been used to reduce the size of invasive implants to nanometer-scaled particles and to anchor, immobilize, or incorporate non-gold molecules or non-gold nano-materials.
To study efficacy and potential side effects for animals and humans, the size, shape, and surface chemistry of GNPs must be carefully defined in terms of the biological properties, including absorption, distribution, metabolism and excretion. A need exists in the art to address the establishment of a platform for observing and tracing GNPs in vivo.